The following invention relates generally to an apparatus used to heat thermoplastic material to effect bending within the thermoplastic material.
Frequently it is desirable to take substantially planar material and bend the material to conform to a finished product. The material to be reformed is formed from a plastic material that is sensitive to heat. This process usually entails placing the thermoplastic material adjacent a source of heat for a period of time, thereby allowing the thermoplastic material to become locally deformable, for subsequent reorientation. Thereafter, the thermoplastic material is removed from the source of heat. As the material cools, it stiffens and retains the shape to which it has been formed.
Although various products currently exist on the market, generally they all include an elongate rod of conductive material which acts as a source of heat because of the resistive nature of the material forming the rod. This localized source of heat when placed in contact adjacent the thermoplastic sheet material allows the plastic to become soft and pliable for subsequent reformation.
One known example is illustrated in U.S. Pat. No. 4,244,771, issued to Pierce and dated Jan. 13, 1981. Pierce teaches the use of a strip heater assembly in which a heating element is supported on a bed of insulating material having an open top wall, the width of which is adjustable to control the magnitude of the heat emanating from the heater. A sheet of material to be deformed is placed above the heater element, resting on top flanges of a housing. In addition, the sheet of thermoplastic material is supported on a top surface of a platform and has an edge which abuts against a stop of a further platform disposed at one end of the assembly. Thus, the appropriate area for heat application is properly indexed and the sheet is sufficiently supported to assure deformation of the sheet only at the desired site. In addition, a plurality of heater elements could be used spaced one from the other.
The included brochures and other literature reflect the state of the art further and all are tendered with the view towards discharging applicant's acknowledged duty to disclose relevant prior art. However, it is stipulated that none of these citations, either singularly or in any conceivable combination teach or render obvious that which is the nexus of the claimed invention.